Circular stingaree
Encyclopedia
The circular stingaree (Urolophus circularis) is an uncommon, little-known species
of stingray
in the family
Urolophidae. Endemic to the coastal waters of southwestern Australia, it prefers a rocky and/or vegetated habitat
. Reaching 60 cm (23.6 in) in length, this species is characterized by an oval pectoral fin disc bearing a striking dorsal pattern of lighter spots and rings, and a central circle of white-margined black spots, on a bluish gray background. Between its nostrils is a skirt-shaped curtain of skin, with the posterior corners drawn out into lobes. Its tail bears a rather large dorsal fin
in front of the stinging spine, and ends in a deep, lance-like caudal fin. Negligibly affected by human activity, the circular stingaree has been listed under Least Concern
by the International Union for Conservation of Nature (IUCN).
, near Fremantle
, Western Australia
. Australian ichthyologist Roland McKay
described it in a 1966 issue of the Journal of the Royal Society of Western Australia, giving it the specific epithet circularis in reference to its shape. Another common name
for this species is banded stingray.
and Rottnest Island
. It is a benthic species that can be found from the shore to a depth of 120 m (393.7 ft), generally sighted over rocks and reef
s, or amongst kelp
.
s with rounded posterior margins. Between the smooth-rimmed nostrils, there is a short, skirt-shaped curtain of skin with the posterior corners extended into lobes. The sizable mouth contains 10 papillae (nipple-shaped structures) on the floor, and small teeth with roughly oval bases. The five pairs of gill slit
s are short. The pelvic fins are small and rounded.
The tail is oval in cross-section and measures about two-thirds as long as the disc, ending in a short, deep, leaf-shaped caudal fin. A relatively large dorsal fin
is positioned on the upper surface of the tail, followed shortly by the serrated stinging spine. The tail lacks lateral skin folds. The skin is entirely smooth. This species is slate-blue above with numerous whitish spots, blotches, and rings, and distinctive large black spots with white borders arranged in a ring at the center of the disc. The dorsal fin and margin of the caudal fin may be brownish. The underside is plain white, becoming light brown on the tail. The largest known specimen is 60 cm (23.6 in) long.
s sustained by maternally produced histotroph ("uterine
milk"). Judging from related species, litter sizes are probably small. Males attain sexual maturity
at below 53 cm (20.9 in) long.
by the small number of scallop
and prawn
trawlers operating in the region, but its preference for rough or vegetated terrain largely shields it from fishing. Therefore, the International Union for Conservation of Nature (IUCN) has listed it under Least Concern
. This species would potentially benefit from the implementation of the 2004 Australian National Plan of Action for the Conservation and Management of Sharks.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of stingray
Myliobatiformes
Myliobatiformes is one of the four orders of batoids, cartilaginous fishes related to sharks. They were formerly included in the order Rajiformes, but more recent phylogenetic studies have shown that the myliobatiforms are a monophyletic group, and that its more derived members evolved their...
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Urolophidae. Endemic to the coastal waters of southwestern Australia, it prefers a rocky and/or vegetated habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
. Reaching 60 cm (23.6 in) in length, this species is characterized by an oval pectoral fin disc bearing a striking dorsal pattern of lighter spots and rings, and a central circle of white-margined black spots, on a bluish gray background. Between its nostrils is a skirt-shaped curtain of skin, with the posterior corners drawn out into lobes. Its tail bears a rather large dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
in front of the stinging spine, and ends in a deep, lance-like caudal fin. Negligibly affected by human activity, the circular stingaree has been listed under Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
by the International Union for Conservation of Nature (IUCN).
Taxonomy
The first known specimen of the circular stingaree was collected off Carnac IslandCarnac Island
Carnac Island is a 19 ha, A Class, island nature reserve about 10 km south-west of Fremantle in Western Australia.-History:In 1803, French explorer Louis de Freycinet, captain of the Casuarina, named the island Île Pelée . It was also known as Île Lévilian and later Île Berthelot...
, near Fremantle
Fremantle
Freemantle is a suburb of Southampton in England.Fremantle or Freemantle may also refer to:- Places :* Fremantle, the port city to the capital Perth, Western Australia...
, Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
. Australian ichthyologist Roland McKay
R. J. McKay
R. J. McKay is an Australia-born biologist known for his work in exotic and translocated freshwater fish in Australia. McKay is curator of fishes at the Queensland Museum and his work has been quoted extensively...
described it in a 1966 issue of the Journal of the Royal Society of Western Australia, giving it the specific epithet circularis in reference to its shape. Another common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
for this species is banded stingray.
Distribution and habitat
Rather uncommon, the circular stingaree has a restricted range off southwestern Australia between EsperanceEsperance, Western Australia
Esperance is a large town in the Goldfields-Esperance region of Western Australia, located on the Southern Ocean coastline approximately east-southeast of the state capital, Perth. The shire of Esperance is home to 9,536 people as of the 2006 census, its major industries are tourism, agriculture,...
and Rottnest Island
Rottnest Island
Rottnest Island is located off the coast of Western Australia, near Fremantle. It is called Wadjemup by the Noongar people, meaning "place across the water". The island is long, and at its widest point with a total land area of . It is classified as an A Class Reserve and is managed by the...
. It is a benthic species that can be found from the shore to a depth of 120 m (393.7 ft), generally sighted over rocks and reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s, or amongst kelp
Kelp
Kelps are large seaweeds belonging to the brown algae in the order Laminariales. There are about 30 different genera....
.
Description
The pectoral fin disc of the circular stingaree is oval in shape and about as wide as long. The anterior margins of the disc are gently convex and converge at a broad angle on the fleshy snout, the tip of which is slightly protruding. The eyes are large, and followed by comma-shaped spiracleSpiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
s with rounded posterior margins. Between the smooth-rimmed nostrils, there is a short, skirt-shaped curtain of skin with the posterior corners extended into lobes. The sizable mouth contains 10 papillae (nipple-shaped structures) on the floor, and small teeth with roughly oval bases. The five pairs of gill slit
Gill slit
Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of Cartilaginous fish such as sharks, rays, sawfish, and guitarfish. Most of these have five pairs, but a few species have 6 or 7 pairs...
s are short. The pelvic fins are small and rounded.
The tail is oval in cross-section and measures about two-thirds as long as the disc, ending in a short, deep, leaf-shaped caudal fin. A relatively large dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
is positioned on the upper surface of the tail, followed shortly by the serrated stinging spine. The tail lacks lateral skin folds. The skin is entirely smooth. This species is slate-blue above with numerous whitish spots, blotches, and rings, and distinctive large black spots with white borders arranged in a ring at the center of the disc. The dorsal fin and margin of the caudal fin may be brownish. The underside is plain white, becoming light brown on the tail. The largest known specimen is 60 cm (23.6 in) long.
Biology and ecology
Little information is available on the natural history of the circular stingaree. It is aplacental viviparous, with the developing embryoEmbryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s sustained by maternally produced histotroph ("uterine
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
milk"). Judging from related species, litter sizes are probably small. Males attain sexual maturity
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
at below 53 cm (20.9 in) long.
Human interactions
Only a handful of circular stingaree specimens have been deposited in museum collections. This species faces no substantial threats from human activity; a few are caught incidentallyBycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
by the small number of scallop
Scallop
A scallop is a marine bivalve mollusk of the family Pectinidae. Scallops are a cosmopolitan family, found in all of the world's oceans. Many scallops are highly prized as a food source...
and prawn
Prawn
Prawns are decapod crustaceans of the sub-order Dendrobranchiata. There are 540 extant species, in seven families, and a fossil record extending back to the Devonian...
trawlers operating in the region, but its preference for rough or vegetated terrain largely shields it from fishing. Therefore, the International Union for Conservation of Nature (IUCN) has listed it under Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
. This species would potentially benefit from the implementation of the 2004 Australian National Plan of Action for the Conservation and Management of Sharks.